Как взять текст из окна, зная его Handle?

Private Declare Function SendMessage Lib 'user32' Alias 'SendMessageA' (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function SendMessageStr Lib 'user32' Alias 'SendMessageA' (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As String) As Long
Private Const WM_GETTEXT = &HD
Private Const WM_GETTEXTLENGTH = &HE
 
Private Sub Command1_Click()
    Dim lngLen As Long
    Dim strBuffer As String
    
    lngLen = SendMessage(TextboxHwnd, WM_GETTEXTLENGTH, 0, 0)
    strBuffer = Space(lngLen)
    Call SendMessageStr(TextboxHwnd, WM_GETTEXT, lngLen, ByVal strBuffer)
    MsgBox strBuffer
End Sub